EC Sensor to Improve Sea Turtle Nesting Research

Even though sea turtles have worldwide distribution, many species are classified as endangered. To help ensure their survival, an important research topic is how sea turtles select their nesting sites along beaches. Several beach parameters have been suggested as possible factors for nesting site selection, including sand salinity, which is determined by measuring the electrical conductivity (EC) of an aqueous solution prepared from mixing a precise mass of the dried sand into a known volume of deionized water, since salinity is proportional to electrical conductivity when adjusted for temperature. Typically, 50 g of dried sand is mixed into 50 mL of deionized water, yielding an evaluation solution. However, this quantity of sand could limit the number of measurements made at a site to avoid disturbing the nest. In this work, a low-cost printed circuit board based planar-electrode EC sensor was developed with relatively large electrodes that was capable of measuring low EC values. Using this sensor, EC measurements were made on sand samples collected near a sea turtle nesting site, requiring only 2 g of dried sand from each sample collection location. This much smaller quantity of sand required for each EC measurement could allow for additional testing samples near a nesting site without adversely affecting it.